This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued.
Certain abbreviations that may be found in the description and/or in the Figures are herewith defined as follows:
ANR automatic neighbour relation
AoA angle of arrival
BCCH Broadcast Control Channel
PDCCH Physical Dedicated Control Channel
PUCCH Physical Uplink Control Channel
ECGI enhanced cell group identity
eNB enhanced Node B
PUSCH physical uplink shared channel
BNB home node B
HeNB home enhanced node B
TAC Tracking area code
OAM operations, administration and maintenance
PCI physical cell identity
PLMN public land mobile network
RAC routing area code
RRC radio resource control
SON self-optimizing network
TA timing advance
TDD time division duplex
TX transmit
UL uplink
RX receive
In Radio access technologies, typically a unique identifier (PCI) is used to identify a cell uniquely in a geographical area. The number of unique available PCI is limited due to the need of orthogonal neighboring PCIs. The PCI serves as the primary identifier for handover procedures. During mobility when neighboring cells measurements are performed by the UE, the UE reports a radio measurement for each PCI it can see. The eNB uses the PCI to map to the matching neighboring cell (EGCI). Then the eNB prepares and initiates handover to the target cell identified by the ECGI. In order to allow successful handovers, the PCI allocation in a neighborhood has to fulfil the condition of confusion-free (i.e., each neighboring ECGI should have a unique PCI value assigned).
If there is PCI confusion (the serving cell of the UE has two neighbors with the same PCI), there is ambiguity in resolving reported PCI to the target cell (ECGI) required by the UE for the handover. If the PCI confusion is left unresolved, then it can lead to handover failures to the target cells. At least user experience is degraded unless the handovers are adapted to work even when PCI confusion exists. Present day standards do support methods to perform PCI confusion detection. Resolving PCI confusion requires the eNB to detect the PCI confusion and perform procedures to resolve the PCI confusion, however the procedures are complex and require operator intervention.
Over time as networks become denser with the introduction of small cells such as Femto cells etc., PCI confusion has become more prevalent. Further PCI confusion resolution can become more complex as the density increases and take longer duration to resolve. Presently standard defined methods to improve handover success rate when PCI confusion exists can result in degradation of user throughput, possible radio loss at the UE and impact to UE battery life as the network tries to adapt HOs to work with PCI confusion.
The example embodiments of the invention as described below work to address at least the issues related to PCI confusion as described above.